<%@page contentType="text/html; charset=utf-8" %>
<!DOCTYPE html>
<html>
<head>
    <title>上机考试管理系统</title>
    <link rel="shortcut icon"type="image/x-icon" href="${basePath}img/logo.png" media="screen" />
    <link rel="stylesheet" type="text/css" href="${basePath}css/login.css">
    <link rel="stylesheet" type="text/css" href="${basePath}css/bootstrap.css" id="boot">
    <script type="text/javascript"  src="${basePath}js/jquery.js"></script>
</head>
<body>
<div class="login-form">
    <h1><b>上机考试管理系统</b></h1>
    <div style="display: flex; flex-direction: row;">
        <p style="font-weight:bolder;">身份</p>
        <div style="display: flex; flex-direction: row;justify-content: space-between; width: 80%;margin-left: 5%;">
            <span><input type="radio" value="1" name="type" checked/>教师</span>
            <span><input type="radio" value="0" name="type"/>学生</span>
            <span><input type="radio" value="2" name="type"/>管理员</span>
        </div>
    </div>

    <div class="txtb">
        <input type="text" id="userName">
        <span data-placeholder="学工号"></span>
    </div>

    <div class="txtb">
        <input type="password" id="passWord">
        <span data-placeholder="学生姓名或密码"></span>
    </div>
    <div class="verify">
        <input type="text" value="" placeholder="请输入验证码（不区分大小写）" class="input-val" >
        <canvas id="canvas" width="100" height="30"></canvas>
    </div>

    <button class="logbtn">登 陆</button>
</div>
<script type="text/javascript">
    var show_num = [];
    draw(show_num);
    $('input[type=radio][name="type"]').on("change", function(){
        if (this.value == "0")
            $('#passWord').attr('type', 'text')
        else
            $('#passWord').attr('type', 'password')
    })

    $(".txtb input").on("focus", function(){
        $(this).addClass("focus");
    });
    $(".txtb input").on("blur", function(){
        if($(this).val() == "")
            $(this).removeClass("focus");
    });
    $("#canvas").on('click',function(){
        draw(show_num);
    })
    $(".logbtn").on('click', function(){
        if (canvasJudge()== 1){ // 提交
            // alert("登录成功!")
            var userName = $("#userName").val().trim();
            var passWord = $("#passWord").val().trim();
            var type = $('input[type=radio][name="type"]:checked').val().trim();

            $.post(
                "login", {"username":userName, "password":passWord, "type":type}, function (response) {
                    if (response[0] != 'p')
                    {
                        alert(response)
                    }
                    else
                    {
                        window.location.href = response;
                    }
                }
            )
        }else if (canvasJudge() == 0){
            alert("验证码错误，请重新输入!");
            draw(show_num);
            $(".input-val").focus();
        }else{
            alert("验证码不能为空!");
            $(".input-val").focus();
        }
    })
    // 验证码判断
    function canvasJudge()
    {
        var val = $(".input-val").val().toLowerCase();
        var num = show_num.join("");
        /* console.log(val, num); */
        if (val == ''){ // 空
            return -1;
        }else if (val == num){ // 输入正确
            return 1;
        }else { // 输入错误
            return 0;
        }
    }
    //生成并渲染出验证码图形
    function draw(show_num) {
        var canvas_width=$('#canvas').width();
        var canvas_height=$('#canvas').height();
        var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
        var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
        canvas.width = canvas_width;
        canvas.height = canvas_height;
        var sCode = "a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
        var aCode = sCode.split(",");
        var aLength = aCode.length;//获取到数组的长度

        for (var i = 0; i < 4; i++) {  //这里的for循环可以控制验证码位数（如果想显示6位数，4改成6即可）
            var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
            // var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
            var deg = Math.random() - 0.5; //产生一个随机弧度
            var txt = aCode[j];//得到随机的一个内容
            show_num[i] = txt.toLowerCase();
            var x = 10 + i * 20;//文字在canvas上的x坐标
            var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
            context.font = "bold 23px 微软雅黑";

            context.translate(x, y);
            context.rotate(deg);

            context.fillStyle = randomColor();
            context.fillText(txt, 0, 0);

            context.rotate(-deg);
            context.translate(-x, -y);
        }
        for (var i = 0; i <= 5; i++) { //验证码上显示线条
            context.strokeStyle = randomColor();
            context.beginPath();
            context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
            context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
            context.stroke();
        }
        for (var i = 0; i <= 30; i++) { //验证码上显示小点
            context.strokeStyle = randomColor();
            context.beginPath();
            var x = Math.random() * canvas_width;
            var y = Math.random() * canvas_height;
            context.moveTo(x, y);
            context.lineTo(x + 1, y + 1);
            context.stroke();
        }
    }

    //得到随机的颜色值
    function randomColor() {
        var r = Math.floor(Math.random() * 256);
        var g = Math.floor(Math.random() * 256);
        var b = Math.floor(Math.random() * 256);
        return "rgb(" + r + "," + g + "," + b + ")";
    }
</script>

</body>
</html>
